Elastic thread and process of making the same



Sept. 15, 1936. s w ALDERFER 2,054,354

" ELASTIC THREAD AND PROCESS OF MAKING THE SAME Filed Dec. 11, 1934 2 Sheets-Sheet l INVENTOR ierling W. Ame rfer ATTORNEY Sept. 15, 1936. s. w. ALDERFER ELASTIC THREAD AND PROCESS OF MAKING THE SAME Filed Dec. 11, 1934 2 Sheets-Sheet 2 |N\ /ENTOR fiierl'in W. Alderfer Patented Sept. 15, 1936,

PATENT OFFICE ELASTIC THREAD AND PROCESS OF MAKING THE SAME Sterling W. Alderfer, Akron, Ohio, asslgnor of one-half to Edward D. Andrews, Akron, Ohio Application December 11, 1934, Serial No. 756,943

13 Claims.

The present invention relates to the manufacture of acomposite thread comprising a central fibrous thread or cord and a covering of rubber which may be suitable for a number of uses, but

is particularly adapted for the manufacture of fabrics by knitting or weaving. The particular object of. the invention is to make a thread for these purposes directly from rubber latex or other rubber or rubber-like material and a central strand of an ordinary thread or cord, by a simple and inexpensive process. The thread in its preferred form is characterized by the fact that it is elastic up to a certain point so that it can be manipulated in the usual machines for making woven or knitted garments, fabrics, webbing or the like. By the process shown and described, it is possible to impart any desired degree of elongation to the thread.

For carrying out the invention either an un'- vulcanized or vulcanized latex may be employed for the outer covering or sheath. In either case the tape should be vulcanized, either wholly or partially before the thread is assembled.

In describing the process and in the claims wherever the generic term latex is used to designate a natural latex, an artificial dispersion of rubber or an artificial rubber dispersion and is intended to be of suflicient breadth to cover these materials whether pre-vulcanized or not.

It will be understood that while the invention is shown and described with sufficient definiteness to enable one skilled in the art to make and use the same, changes and modifications are possible by which the invention may be employed in other forms than that shown herein.

In the drawings in which the best known method of practicing the inventionis illustrated:

Figure 1 is a side elevation of an apparatus such as may be used in the manufacture of the elastic thread;

Figure 2 is a plan view thereof;

Figure 3 is an enlarged view of the completed thread, parts being cut away to disclose the internal structure of the composite thread;

Figure 4 is a plan view of the manufacturing unit;

Figure 5 is an enlarged cross-section of the forming roll; and

Figure 6 is a detail view showing the thread lying on the forming roll. I

The invention comprises the steps of forming a tape or band of rubber, preferably directly from latex, which may be pre-vulcanized, that is to say a latex in which the rubber constituent is vulcanized while still in the. dispersed phase, so that by merely drying, the rubber is obtained in fully vulcanized condition. While the tape is still in a slightly tacky condition, the thread is covered by rolling the tape upon itself to form a tubeand a thread of cotton, silk or other material is 6 introduced into the tube. In order that the resultant composite thread will be elastic, the rubber tape is under tension while the tube is being formed and while the thread is being incorporated therein so that after the forming opera- 10 tion, when the tension is released, it will contract upon the cord and give a suflicient degree of elongation for the desired purposes.

The rubber tape is formed by depositing a film of the latex by any desirable means upon a belt 15. or endless band I which is conducted through a Y drying chamber for a sufficient distance to dry substantially. In such condition the tape is selfsustaining, will withstand the tension exerted thereon in the subsequent processes and can be rolled into tubular form. Apparatus for this general purpose is well-known and it is not considered necessary to disclose it in detail.

As the tape, which is indicated at 2, leaves the belt it passes over the stripping roll 3, being preferably placed under some tension by driving the roll at a speed slightly in excess of the surface speed of the belt. The tape then passes over the roller 4 which is driven at a still further accelerated surface speed so as to impart additional tension to the tape. From the roller 4 the tape passes to the tube forming roll 5, one side of which is provided with the tapering or conical flange 6. This flange is so located with respect to the line of travel of the tape edge, that the edge of the tape is rolled upon itself. as it progresses through the machine. Further tension may be applied to the tape between the rolls 4 and 5. From the roll 5 the finished product passes around the roll I which is driven at the same surface speed as the roll 5 to feed the tape through the apparatus.

At the point where the covering of the thread occurs, the tape receives the inn d or thread which restricts its expansion. This hread is indicated at 10 and may be of any desired material. 45 As almost all threads are formed by twisting together several component strands, the thread is usually capable of longitudinal contraction. The thread is supplied from a spool H and passes through a guiding and tensioning device such as 0 indicated at l2, by which it is guided-into the edge of the tape as it is rolled upon itself. This action places the thread in the edge of the tape so that when the composite thread is completed it is surrounded by several convolutions of the rubiii and is driven by gearing BS from the shaft lb.

The shaft it carries a series of stepped pulleys 20 which are connected by belt 2! with a complementary set of stepped pulleys 22 on the shaft-23 which carries the turning roll 5. Varying degrees of tension may be imparted to the tubular rubber at various points of the travel of the tape, or as it is being formed, by shifting the belt 2! through the belt shifter 24. The roll lis driven at the surface speed of the roll K? through gearing indicated at 25 in Figure 4.

The roll 5 and flange 6 constitute a practical Q and very simple means for covering the thread with the tubular envelope or sheath, although other or equivalent means may be substituted for this device, so long as the action does not spirally roll the tape. The extent to which the tape may be rolled is governed by the position of the flange 6 with respect to the edge of the tape, and this may be controlled by shifting the roll along its axis by the lever 23 and the spanner 29 which engages the groove to. For this purpose the roll 5 is splined to the shaft 23 as shown in Figure 5.

The elastic thread is shown in cross-section in Figure 6 as it. lies atthe base of the flange 6, the thread being enclosed in the several convolutions of the tape as shown, the number ofv convolutions being determined by the width of the .tape. As shown in Figure 3 when the composite thread contracts, as it will when the tension is relieved, the thread It will be compacted longitudinally as shown in Figure 3 which will cause the twists in the thread to open up. In this way crinkling or kinkiness of the elastic thread is avoided. The finished product will stretch or elongate until the thread it reaches its original condition. If the a thread is twisted so that it has some elasticity of itself, of course the composite thread will stretch until the point or maximum stretch of the thread it is reached.

The valuable features of the invention consist, in the main, of the production of a thread which is elastic but which also has the property of resisting further elongation after a certain point is reached. ,It is possible, therefore, to use this rubber from a latex solution. stretching the tape from a latex solution, and rolling the tape around,

a thread while the tape is under longitudinal tension, the thread having a limit of elongation less than the rubber.

attests comprising forming and substantially drying a rubber tape from a latex solution, and rolling the tape to form a. tubular covering around a fibrous thread, the rubber component being under tension when the fibrous thread is incorporated there=- with.

i. The process of making an elastic thread comprising forming a tube of rubber by rollinga {rubber tape upon itself, and incorporating a fibrous thread in the tube during the rolling operation, the rubber being under longitudinal tension during the process.

5. The process of making a composite elastic thread having a fixed degree of elongation comprising forming a rubber tape by depositing a film of latex and drying the same sufliciently to be self-sustaining, rolling the tape while under lom= gitudinal tension to form a tube, and incorporating an untensioned fibrous thread in the tube during the rolling operation.

6. The process of making an elastic thread comprising forming a rubber tape by depositing a mm of latex and drying the same sufiiciently to be self-sustaining, stretching the tape progressively and while the tape is under tension rolling the tape upon itself to form a tube, and inccr porating a fibrous thread in the tube during the rolling operation.

7. A composite elastic thread comprising a tubular envelope of rubber and a central thread therein having a degree of elongation less than the envelope, the central thread being compacted longitudinally beyond its normal condition and held in compacted condition by the contraction of the envelope so that the composite thread is capa ble of elongation to the normal condition of the central thread.

8. A composite elastic thread comprising a tubular envelope of rubber and a central thread within the envelope, said thread having a degree of elongation less than the envelope, the thread being compacted longitudinally beyond its normal condition and held in compacted condition by the contraction of the envelope so "that the composite thread is capable of elongation to a point determined by the central thread.

9. A composite elastic thread having a definite degree of elongation comprising a tubular envelope of rubber and a. thread element therein, said thread having a degree of elongation less than the envelope, the thread element being normally straight, the strands of which are compacted longitudinally and held in such condition by the contraction of the envelope so that-the. composite thread is capable of elongation determined by the threadelement.

10. A composite elastic thread comprising a tubular envelope of dried latex and a central thread therein, the central thread being compasted longitudinally beyond its normal condition and held in compacted condition by the contraction of the envelope so that the composite thread is capable of elongation determinedby the normal condition of the central thread.

ll. A composite elastic thread comprising a tubular envelope of dried latex and a central thread within the envelope, the thread being compacted longitudinally beyond its normal condition and held in compacted condition by the contraction of the envelope so that the composite thread is capable of elongation to a point determined by the central thread.

12. A composite elastic thread having a definite degree of elongation comprising a tubular envelope of dried latex and a thread element therein, the thread element being normally straight, the strands of which are compacted longitudinally and held in such condition by the contraction 'of the envelope so that the composite thread is capable of elongation determined by the thread element.

13. A composite elastic thread comprising a tubular envelope of rubber and a central thread having-a different capacity of elongation than the envelope located within the envelope, the thread being compacted radially and longitudinally by I the contraction of the envelope.

STERLING W. ALDERFER. 

